Panic attacks or panic disorder before age 50 was associated with a 38% increased risk of MI and a 44% higher risk of coronary heart disease diagnosis, Kate Walters, M.D., Ph.D., of University College London, and colleagues reported online in the European Heart Journal.

In the large cohort study, panic-prone patients over 50 were also at a modestly elevated risk of coronary heart disease (hazard ratio 1.11, 95% confidence interval 1.03 to 1.20).

However, their heart disease mortality rates were slightly reduced at all ages compared with controls (HR 0.76, 95% CI 0.66 to 0.88), suggesting a "potentially complex relationship," the researchers said.

The symptoms of panic attacks -- which include sudden onset of palpitations and chest pain -- can closely mimic an acute cardiac event, the researchers noted.

These links could be because heart disease was initially misdiagnosed as panic or because of a true causal association through activation of the sympathetic nervous system, increased atherogenesis, and reduced heart rate variability, Dr. Walter's group said.

The researchers favored the causal explanation because the increased heart disease risk associated with panic was maintained over time.

Either way, though, "clinicians should be vigilant for this possibility when diagnosing and treating people presenting with symptoms of panic," they wrote.

They noted that the risk in their study was lower than the three-fold risk of heart attack or stroke and doubled risk of all-cause mortality associated with panic attacks among postmenopausal women in the Women's Health Initiative study. (See: Panic Attacks Linked to Cardiovascular Events and Death)

In the instant study, the researchers analyzed data for 57,615 individuals 16 and older with a diagnosis of panic disorder or panic attacks recorded in electronic medical records of up to 650 general practices participating in the British General Practice Research Database from 1990 through 2002.

This represented an overall 1.1% prevalence of panic disorder or attacks.

Each case was age- and sex-matched to a random sample of six patients without panic attacks or disorder in the same database.

After adjustment for age, sex, socioeconomic factors, traditional risk factors for heart disease, and psychiatric co-morbidity, a diagnosis of panic disorder or attacks was associated with a significantly increased risk of MI in younger individuals (HR 1.38, 95% CI 1.06 to 1.79), but not those 50 or older (HR 0.92, 95% CI 0.82 to 1.03).

Young women 16 to 39 at study entry were particularly at risk, with a 3.34 times higher incidence of coronary heart disease compared with controls (95% CI 1.59 to 7.02).

A trend also appeared for greater MI risk the more panic attacks a patient had recorded in the database before age 50, but the researchers cautioned that this was based on low event numbers and wide confidence intervals.

But the coronary risk associated with panic disorder and attacks was significant at all ages (HR 1.44 under 50, 95% CI 1.25 to 1.65, and HR 1.11 for 50 and over, 95% CI 1.03 to 1.20).

Again, women under 40 were most at risk, with 3.03-fold higher coronary heart disease risk than those without panic disorder or attacks (95% CI 2.15 to 4.27) and the more panic attacks over the years the more the risk tended to increase.

One potential reason for the differences between age groups may be a lower rate of initial misdiagnosis in older patients because clinicians are more cautious to exclude heart disease when making initial panic diagnoses in older adults.

An alternative explanation is that the "small increases in atherogenesis caused by sympathetic nervous system activation in panic disorder are overtaken by a more dominant underlying age-related atherogenesis in older people, thus masking the relative risk attributed to panic in older age groups," Dr. Walters' group wrote.

The explanation for this could be that the younger age groups with the highest risk associated with panic had few cardiac deaths, the researchers said.

Or, people diagnosed with panic disorder or attacks may have an advantage by being in the medical system such that they present earlier and provide their physician more frequent opportunity to identify and treat heart problems before they become fatal, they suggested.

However, the investigators cautioned that there was the possibility for unmeasured confounding and diagnostic bias, "in that some general practitioners might tend to under-report both coronary heart disease and panic disorder."

But, they said, the results are broadly generalizable to other countries with a similar socio-demographic structure.

The study was funded by the Medical Research Council.

The researchers reported no conflicts of interest.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco

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